S. A. Grudinkin

Luminescent isolated diamond particles with controllably embedded silicon-vacancy colour centres

A technique to fabricate isolated diamond particles with controllably embedded silicon-vacancy (Si-V) colour centres is described. Particle growth and Si doping are performed by microwave plasma-enhanced chemical vapour deposition (CVD) using silane as a source of impurity atoms. The Si-V centres have a strong narrow-band photoluminescence (PL) at room temperature. The dependence of PL intensity of the 738 nm zero-phonon line (ZPL) on silane concentration in the feed-gas mixture exhibits a pronounced maximum. A comparison of the PL and Raman spectra shows that there is an evident correlation between the ZPL intensity and the presence of structural defects and nondiamond carbon phases that act as nonradiative recombination centres suppressing radiative recombination. The results open the door for using the powerful CVD technique for large-scale production of photostable near-infrared single-photon emitters and noncytotoxic biomarkers.

Effect of tetraethoxysilane pretreatment on synthesis of colloidal particles of amorphous silicon dioxide

The effect of the time passed after tetraethoxysilane treatment with ammonia on the diameter of particles produced by tetraethoxysilane hydrolysis in alcohol-water-ammonia media is studied. The regulation the time passed after of tetraethoxysilane treatment results in the synthesis of submicron monodisperse spherical silica particles with diameters differing by a factor of two. The difference is explained by the formation of SiO2 particles with sizes of 10–100 nm in tetraethoxysilane during 10–30 h after treatment with ammonia. These particles enhance the concentration of nucleation centers in a reaction mixture, thus decreasing the final size of monodisperse silica spheres. Opal films with a high structural perfection and pronounced photonic crystal properties are grown based on the obtained monodisperse SiO2 particles.

Polarized infrared and Raman spectroscopy studies of the liquid crystal E7 alignment in composites based on grooved silicon

Alignment of liquid-crystal filler molecules and the electro-optical effect in composite photonic crystals based on grooved silicon are studied. It is found that the nematic liquid crystal molecules that fill the grooves are predominantly aligned in a planar configuration with respect to the silicon walls. The liquid crystal molecules are realigned homeotropically with respect to the groove walls under the influence of an electric field. The effect detected can be used to adjust the photonic band gap of a one-dimensional photonic crystal.

Chemical vapor deposition of isolated spherical diamond particles with embedded silicon-vacancy color centers onto the surface of synthetic opal

Isolated spherical diamond particles with embedded silicon-vacancy color centers are synthesized on a patterned surface of synthetic opal by chemical vapor deposition methods. The phase composition of the particles is determined and their structural and luminescence properties are studied. Prospects are discussed for the application of these particles as integrated spherical diamond microcavities, in which color centers are situated directly in the microcavities.

Activator-free luminescent nanocontainers for theranostics of cancerous growths

Single-stage synthesis has been used to obtain submicrometer monodisperse spherical mesoporous silica particles exhibiting bright wide-band luminescence in the visible spectral range. The particles have a specific surface area of 550 m2/g, pore volume of 0.36 cm3/g, and average pore diameter of 0.3 nm. The synthesis technology provides formation of an active inner surface (surface of mesopores), which will enable binding and retention of medicinal preparations upon their introduction into the particles. The particles are promising for application in theranostics of cancerous growths as nanocontainers simultaneously serving as biomarkers.

Infrared spectroscopy of silicon carbide layers synthesized by the substitution of atoms on the surface of single-crystal silicon

This paper presents the results of the infrared spectroscopic study of silicon carbide epitaxial layers grown by the substitution of atoms on the surface of single-crystal silicon. It has been found that, in the infrared spectra, there is a band at 798 cm–1, which corresponds to a transverse optical (TO) phonon in the lattice of silicon carbide. The parameters of disordered silicon carbide on the surface of pores between the epitaxial layer of silicon carbide and the silicon substrate have been determined. It has been revealed that, in the infrared spectra of silicon carbide, there is a band in the wavenumber range of 960 cm–1. A hypothesis has been proposed, according to which this band corresponds to the energy of the previously theoretically predicted elastic dipole consisting of an elastically interacting carbon atom located in an interstitial position and a silicon vacancy.

Fluorescent monodisperse spherical particles based on mesoporous silica containing rhodamine 6G

Fluorescent monodisperse spherical silica (SiO2) particles with a regular mesoporous structure containing encapsulated Rhodamine 6G (R6G) dye have been synthesized. The as-synthesized particles have been coated with SiO2 and SiO2-CTAB (cetyltrimethylammonium bromide, C16H33N(CH3)3Br) shells in order to prevent uncontrolled release of the dye from pores. The kinetics of R6G release from the pores of silica particles has been studied. It has been found that the particles synthesized by adding CTAB and R6G to the reaction mixture, as well as the particles coated with the SiO2-CTAB shell, are characterized by the maximum duration of dye release from the pores, which is probably associated with the formation of chemical bonds between R6G and CTAB molecules.

Diamond films: Initial CVD growth stage using nanodiamonds as nucleation centers

Scanning electron microscopy is used to study features of a mechanism operating in the initial growth stages during the CVD of diamond films on nucleation centers representing predeposited nanodiamonds obtained by method of detonation synthesis.

Growth of Diamond Films on Crystalline Silicon by Hot-Filament Chemical Vapor Deposition

The effect of hot-filament chemical vapor deposition conditions on the phase composition of diamond films grown on a silicon substrate was studied. The growth conditions providing the highest content of diamond phase at a growth rate of about 1 µm/h were ascertained.

Ge-Te-Se and Ge-Te-Se-S alloys as new materials for acousto-optic devices of the near-, mid-, and far-infrared spectral regions

The optical, acoustic, and acousto-optic properties of new Ge-Se-Te-S and Ge-Se-Te alloys are studied. As a result of parameter optimization, efficient acousto-optic materials transparent in a wide infrared range (λ = 1.5–18 μm) are fabricated.